Commander of the Warsaw ghetto uprising was born in a poor family in a poor neighborhood. After he completed his high school studies, he joined the "Hashomer Hatzair" youth movement. As a youngsters guide he excelled as a leader and organizer.

In September 7, 1939, a week after the war broke out, Anielewicz escaped with his youth movement friends from Warsaw to the east regions, assuming that the Polish army would restrain the German advance. In September 17, the Soviet army occupied the eastern regions of Poland. Anielewicz tried to pass the border to Romania to open a route for youngsters to Israel. Anielewicz was caught and put in a Soviet jail. After he was released he returned to Warsaw Ghetto passing through a lot of communities on his way.

Anielewicz stayed in Warsaw a short time and left for Vilna, Lithuania, where a lot of refugees, youth movement's members and political groups came from the west. The city was annexed to the USSR a short time before.

Anielewicz demanded from his colleagues to send back a group of members to the occupied territories in Poland to continue the educational and political activities underground. He and his girlfriend, Mira Fukrer, were among the first volunteers that went back to Warsaw.

From January 1940, Anielewicz became a professional underground activist. As a leader of his youth movement, he organized cells and youngsters groups, instructed, participated in underground publications, organized meetings and seminars and visited other groups in different cities.

Anielewicz dedicated part of his time learning Hebrew, reading and studying History, sociology and economics. At the same time his point of view was formatted and expressed in publications and lectures.

His activities changed when the news about the mass killings of Jews in Eastern Europe were known. Immediately Anielewicz start organizing self-defense groups inside the Warsaw Ghetto. His first attempts to connect with Polish forces outside the Ghetto, acting under orders of the Polish government in London, failed. In March - April 1942, Anielewicz was one of the founders of the "Anti-fascist group". The "group" did not fulfill the expectations of Zionist groups, and, after a wave of arrests of communist members the organization, was dismantled.

When the major deportation to extermination camps started in Warsaw Ghetto, in the summer of 1942, Anielewicz was visiting in the south-west region of Poland, that was annexed to Germany, trying to organize armed defense. At his return he found only 60,000 Jews from 350,000, and a small "Jews Fighter Organization", without any weapons and with a lot of difficulties, a lost of fighters and failures. Anielewicz started to reorganize the group with great success because there was much support for the idea of fighting after the major deportation of all the underground groups. Next step was to compose a public committee and a coordination committee. In November 1942 Anielewicz was elected as chief commander. Until January 1943, a few fighter groups of youth movement members were based in the ghetto. A connection with the Polish army commanded from London was made and weapons were supplied from the Polish side of the city.

In January 18, 1943, the Nazis planned the second big deportation of the Jews to the extermination camps from the Warsaw Ghetto. The headquarters organization did not have enough time to discuss the possible response but the armed groups decided to react. The resistance was lead in two points. Anielewicz commanded the battle in the main street. The fighters joined the deported and when they got a signal between the streets Zamenhoff and Niska they attacked the escort. The Jews escaped and dispersed. Most of Hashomer Hatzair's members were killed in this battle. This was a very significant move because four days after the revolt, the Nazis stopped the operation.

The next three months - January to April 1943 - was an intensive preparation and very decisive period for the underground organization, under Anielewicz's command. In April 19, on the eve of Pesah, the last deportation began, and the uprising broke out. At the first the superiority of the resistance was clear, and the Nazis suffered many losses. Three long days of battles between streets took place. The Nazis greatly outnumbered the resistance in soldiers and weapons, so that the hundreds of fighters, with only hand revolvers, had no chances. However, the Jewish fighters didn't surrender, and even survivors in shelters did not exit them despite the calls and promises. The Nazis forces were compelled to burn house by house and to go through every shelter in the Ghetto. The fight lasted for four weeks, and in May 16, 1943, after a lot of casualties, General Jurgen Stroop could report that the Ghetto was defeated and "there is no more Jewish suburb in Warsaw".

The first days of battles Anielewicz commanded the resistance forces. When the street fight ended he moved to the headquarters shelter to Mila 18 street. On May 8, Anielewicz was killed in the headquarters bunker together with a few colleagues.

In Israel Kibbutz, "Yad Mordechai" was named in memory of Mordecai Anielewicz, and a monument is erected in his memory.